How to unlock the Phenom's fourth core

Push AMD's triple core to the limit!

When AMD launched its first triple-core processor, we laughed at both them and the CPU itself. Oh, how we laughed.

Even the weakly clocked quad-core versions of the first Phenoms were farcical and their bastard offspring, with three-quarters the appendages, were at best pointless.

Things have changed now though – seriously so. The release of the Phenom II with its speedier clocks, more elegant architecture and massive overclocking headroom has given AMD a family of chips that, while not on a par with the lightning Core i7, at least gives it a run for its money.

The triple-core version of the Phenom II has come into its own too. No longer is it a comically irrelevant chip; the fact that we still lack many multi-core apps or games means the price and raw clockspeed of the processor keep it at the races.

The other neat thing, though nowhere near as certain as the overclocking potential, is the fact that certain chips carry the possibility of unlocking a dormant fourth core. The triple-core Phenom IIs are essentially quad-core CPUs with one of the cores turned off. Inevitably that core has been turned off for a reason, usually owing to a fault in the silicon, but not always.

Some batches are designated to be sold as triple-core chips despite being manufactured in the same process as quad-cores. It's all down to modern economics and business practices. AMD isn't going to be able to sell every single yieldable quad-core it manufactures, so some will be 'down-binned' to cover demand for cheaper processors.

If you're lucky enough to get hold of one of these then chances are you're in for a lovely free core.